Solid-State Image Sensor Optical Black Area Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solid-state image sensors face challenges in enhancing image quality, particularly in high-sensitivity and long-exposure modes, due to variations in black level signals caused by temperature and exposure time, which affect the accuracy of black level correction.
Innovation Solution
The solution involves a solid-state image sensor with an effective pixel area and an optical black area where zones with and without photodiodes are alternately arranged at predetermined intervals, allowing for selective clamping of horizontal scanning lines to stabilize the black level, and using multiple types of pixels in the optical black area to accurately correct the black level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical black area with shield layer is used, then the black level reference is obtained, but the black level varies due to temperature and exposure time causing dark regions to become flat black or light
Solution Approach 1:
The optical black area is segmented into multiple types of pixels (first type without photodiode, second type with photodiode but no color filter, third type with complete structure but optically shielded). Each segment responds differently to temperature and exposure conditions, allowing selection of the most appropriate reference signal under varying operating conditions.
Solution Approach 2:
The patent changes the structural parameters of pixels in the optical black area by creating different types with varying degrees of optical shielding and photodiode configuration. This allows the system to adapt to different temperature and exposure time conditions by selecting from multiple pixel types, thereby maintaining stable black level reference across varying operational parameters.
2Measurement precision
If multiple optical black areas are arranged above and below the effective pixel area, then black level reference can be obtained, but the device complexity and control processing requirements increase
Solution Approach 1:
Multiple functional types of pixels (different optical black pixel types) are merged into a single integrated optical black area. This consolidation provides multiple black level reference sources without requiring separate optical black areas positioned above and below the effective pixel area, thereby reducing device complexity while maintaining measurement precision.
3Reliability
If zones with photodiodes and zones without photodiodes are alternately arranged in the optical black area, then selective clamping of horizontal scanning lines stabilizes the black level, but the manufacturing precision requirements increase
Solution Approach 1:
The optical black area is segmented into alternating zones with and without photodiodes, creating distinct functional regions that can be selectively clamped. This segmentation provides multiple black level references under different operating conditions, improving reliability while the regular alternating pattern facilitates manufacturing through standardized fabrication processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances image quality by accurately correcting the black level, preventing dark regions from becoming overly black or light, and maintaining stability across varying exposure conditions.
Implementation Method 1
an effective pixel area which has a plurality of photosensitive cells arranged for each generating a signal charge corresponding to an amount of incident light
Implementation Method 2
an optical black area shielded from the incident light. The optical black area is positioned at the front and rear sides of horizontal scanning lines
Data Source
AI summary
A digital camera includes an image sensor having an array of CCD (Charge-Coupled Device) cells on which an optical image is focused via a lens and a shutter. The image sensor produces an image signal by photoelectric conversion. The image signal is clamped by an analog front end circuit, which feeds a processed analog signal to an analog-to-digital converter. The resultant digital signal is input to a signal processor. The analog front end circuit switches horizontal scanning lines to be clamped in accordance with image pickup information. The horizontal scanning lines to be clamped lie in an optical black area where a photodiode is included in each CCD cell or an optical black area where the former is not included in the latter.